Colchicine

Colchicine is a very old drug and is made from the Autumn Crocus, Colchicum autumnale (a poisonous European flowering plant). It has been primarily used in the treatment of gout. Although it is not formally indicated or approved for the treatment of dermatological diseases, colchicine has been prescribed for some skin conditions with good results. Its effectiveness is due to several immunological and anti-inflammatory properties.

In New Zealand colchicine is available as 0.5mg tablets (previously 0.6mg).

Colchicine for dermatological diseases

Colchicine in varying dosages is used for a number of dermatological diseases. Its effectiveness has only been shown through the treatment of small and mostly uncontrolled study groups.

Other dermatological conditions that may be treated with colchicine include linear IgA dermatosis, acquired epidermolysis bullosa, vasculitis, morphoea and dermatomyositis.

More controlled and double-blind studies are needed to prove the usefulness of colchicine in dermatological diseases.

Contraindications

Colchicine should not be used under the following circumstances:

• Patients with a known hypersensitivity (allergy) to the medicine
• Patients with serious gastrointestinal, kidney, liver or heart disorders
• Patients with blood diseases in which there are low numbers of white cells or platelets

Precautions

Colchicine can be fatal in overdose. Treatment with colchicine should be stopped immediately when abdominal pain, diarrhoea, nausea or vomiting occur. These are the first signs of toxicity and usually occur between 0-24 hours after taking the medicine.

Side effects

The most common side effects are abdominal pain, diarrhoea, nausea or vomiting, which occur in up to 80% of patients receiving a maximal dose. Gastrointestinal symptoms are worse at higher dosages. These symptoms are a good indication that toxicity is approaching and the medicine should be stopped.

Other side effects include:

• Bone marrow depression resulting in agranulocytosis (absent white blood cells) and thrombocytopaenia (low numbers of platelets)
• Peripheral neuritis (nerve inflammation affecting hands and feet)
• Purpura (bleeding into the skin)
• Myopathy (weak muscles)
• Loss of hair
• Azoospermia (absent sperm production).

Colchicine, when used in low doses, has a low rate of side effects. Beneficial effects without the side effects is possible by reducing the dosage.